Ligand-Controlled Chemodivergent Bismuth Catalysis
Lucas Mele, Philipp D. Engel, Jamie A. Cadge, Vytautas Pečiukėnas, Hoonchul Choi, Matthew S. Sigman, Josep Cornellà
Abstract
High Resolution Image Download MS PowerPoint Slide Herein, we report a ligand-controlled chemodivergent bismuth-catalyzed coupling between arylboronic acids and N -fluorosulfonimide derivatives that enables the selective formation of either C(sp 2 )–N or C(sp 2 )–O bonds. Selectivity is achieved by the modulation of the electronic and steric properties of a common ligand framework for bismuth, thus establishing an unusual ligand-controlled chemodivergent platform in main group catalysis. Specifically, the use of an electron-enrich sulfone ligand led to the major formation of sulfonimide with selectivities ranging from 2:1 to more than 20:1. Conversely, a bismuth catalyst supported by an electron-deficient sulfoximine predominantly promoted the sulfonimidate product with ratios ranging between 5:1 and 15:1. To understand the underlying principles that control the selectivity, a comprehensive mechanistic investigation was conducted by combining experimental stoichiometric studies, DFT calculations, and statistical modeling. These studies support a catalytic high-valent bismuth redox cycle, where Bi(V) intermediates dictate product selectivity through either a three- or five-membered reductive elimination–ligand coupling event. By means of statistical modeling, we identified that the charge of the coordinating heteroatom through hypervalency, together with a steric parameter around the bismuth, is the key parameter responsible for the stabilization of the relevant transition states that lead to control over the reductive elimination process.